A wide variety of viral infections exist in humans and the symptoms of infection, time course of infection, and mechanisms of viral replication differ depending on the type of virus. For example, the time course of the primary infection of some viruses, such as influenza and measles, ranges from several days to several weeks, and in contrast, the time course of viruses such as human immunodeficiency virus (HIV), herpesvirus, and papillomavirus, which may be months to years and beyond.
In addition to primary infection, some viruses, for example the herpesviruses, can also cause persistent or latent infections. Herpesviruses persist in a subject by establishing long-term latency in some cells. In the latent state, the viruses do not evoke the normal immune response, but the latency is not absolute, and at times the latent herpesviruses may be reactivated. Herpesviruses are also shed intermittently or continuously at a low level by healthy humans, thereby continuing the potential for viral infection in other individuals. (see Harrison's Principles of Internal Medicine, 14/e, McGraw Hill Companies, New York, 1998).
Epstein-Barr virus (EBV) is an example of a commonly occurring member of the herpesvirus family, which also includes other members such as: herpes simplex virus 1, herpes simplex virus 2, and varicella zoster. Epstein-Barr virus (EBV) is a 165-kb double-stranded DNA virus of the herpesvirus family that replicates as an episome in latently infected cells. B cells or epithelial cells are latently infected by EBV in 90% of humans and can cause lymphoproliferative disease in immunosuppressed subjects and carcinomas. To prevent this problem in patients with AIDS or those who are therapeutically immunosuppressed following transplantation, there is a critical need for strategies to interfere with the EBV infection process.
Acute infection with EBV reportedly is the cause of infectious mononucleosis and is also known to be associated with human tumors including nasopharyngeal carcinoma, Burkitt's lymphoma, Hodgkin's disease, and B cell lymphoma, each of which may arise as a secondary effect of the EBV infection. Additional secondary conditions that may also be associated with EBV infection include autoimmune disorders such as rheumatoid arthritis and Sjögren's syndrome.
The available treatment options for EBV infection include palliative support and symptomatic treatments such as rest and pain relievers. There are no available methods to prevent EBV infection or to eliminate the virus from latently infected cells. Options for reducing the likelihood of contracting a viral infection, such as an EBV infection, and treatments for existing EBV infection are critical to reduce the number of primary and secondary complications of this viral disease.